Title: A 50-100 kWe gas-cooled reactor for use on Mars.

Abstract

In the space exploration field there is a general consensus that nuclear reactor powered systems will be extremely desirable for future missions to the outer solar system. Solar systems suffer from the decreasing intensity of solar radiation and relatively low power density. Radioisotope Thermoelectric Generators are limited to generating a few kilowatts electric (kWe). Chemical systems are short-lived due to prodigious fuel use. A well designed 50-100 kWe nuclear reactor power system would provide sufficient power for a variety of long term missions. This thesis will present basic work done on a 50-100 kWe reactor power system that has a reasonable lifespan and would function in an extraterrestrial environment. The system will use a Gas-Cooled Reactor that is directly coupled to a Closed Brayton Cycle (GCR-CBC) power system. Also included will be some variations on the primary design and their effects on the characteristics of the primary design. This thesis also presents a variety of neutronics related calculations, an examination of the reactor's thermal characteristics, feasibility for use in an extraterrestrial environment, and the reactor's safety characteristics in several accident scenarios. While there has been past work for space reactors, the challenges introduced by thin atmospheres like those on Marsmore » have rarely been considered.« less

@article{osti_886894,
title = {A 50-100 kWe gas-cooled reactor for use on Mars.},
author = {Peters, Curtis D.},
abstractNote = {In the space exploration field there is a general consensus that nuclear reactor powered systems will be extremely desirable for future missions to the outer solar system. Solar systems suffer from the decreasing intensity of solar radiation and relatively low power density. Radioisotope Thermoelectric Generators are limited to generating a few kilowatts electric (kWe). Chemical systems are short-lived due to prodigious fuel use. A well designed 50-100 kWe nuclear reactor power system would provide sufficient power for a variety of long term missions. This thesis will present basic work done on a 50-100 kWe reactor power system that has a reasonable lifespan and would function in an extraterrestrial environment. The system will use a Gas-Cooled Reactor that is directly coupled to a Closed Brayton Cycle (GCR-CBC) power system. Also included will be some variations on the primary design and their effects on the characteristics of the primary design. This thesis also presents a variety of neutronics related calculations, an examination of the reactor's thermal characteristics, feasibility for use in an extraterrestrial environment, and the reactor's safety characteristics in several accident scenarios. While there has been past work for space reactors, the challenges introduced by thin atmospheres like those on Mars have rarely been considered.},
doi = {10.2172/886894},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Sat Apr 01 00:00:00 EST 2006},
month = {Sat Apr 01 00:00:00 EST 2006}
}

Five thermionic reactor types were studied for use in the power range of 50 to l00 kW(e). These were (1) an all-cell U-235 reactor which is larger than necessary and turned down to l00 kW(e), (2) an all-cell U-233 reactor, (3) a reactor with /sup 235/UN driver elements in addition to thermionic fuel elements, (4) a reactor with /sup 235/U- ZrH driver elements and the same Mark VIIB thermionic elements (1.l in. diameter by 2 in. long emitter) used in the fast reactors, and (5) a reactor with U- ZrH driver elements and Mark VIIA thermionic elements (0.63 in. diametermore » by 2 in. long emitter). Performance comparisons in terms of power plant weight showed that the all-cell U-233 reactor was by far the best, while the all-cell U-235, UN driver, and Mark VIIB U - ZrH reactors all have similar intermediate performance, and the Mark VIIA U- ZrH reactor has the poorest performance. The Mark VIIA U-ZrH driver reactor was also difficult to control with poison-backed reflector drums and was found to require several modifications including a large increase in the diameter of the control drums to obtain adequate control. A comparison of the dynamic behavior of the UN driver reactor with that of the U-235 all-cell reactor showed that the prompt negative reactivity coefficient due to expansion of the driver elements could prevent rupture of the thermionic fuel element cladding for accidental rates of reactivity insention of to per second. 5 references. (auth)« less

The Los Alamos Scientific Laboratory is studying various reactor power plants for space applications in the range of 10 to 100 kWe to meet space missions in the late 1980's and 1990's. The study is concentrating on a high-temperature, compact, fast reactor that could be coupled with various radiation shielding systems and thermoelectric, thermionic, or dynamic electrical power conversion systems, depending on the mission. Though the study is continuing, this report provides a description of what a typical power plant might contain in the time period and at the power levels of interest.